Articles such as infant diapers, adult continence garments, feminine napkins and the like have been manufactured generally by processes where parts or components of the article are deposited on a continuously moving product web. Often, the speed with which the parts or components are produced and fed into the process is not the same as the speed of advance of the product web itself. In such cases, the speed of production and/or deposition of the component parts on the moving web must be varied to match the speed of the product web to properly match the parts to the moving web without adversely affecting the process or finished article.
Several methods for changing the speed of a part or component of material for deposition on a continuously moving web are known in the art. One method employs rollers segmented into sections which are inwardly and outwardly moveable in a direction radial to their direction of rotation. As the roller rotates, the segments are driven by cam actuating or gearing means to move inwardly and outwardly changing the linear surface speed of the roller segments as the roller rotates through each revolution.
Another method utilizes festoons to reduce the speed of the moving web to which the parts or components are to be applied. The continuously moving web is temporarily slowed to the speed of the component parts to be deposited. with the excess portion of the continuously moving web gathering in festoons. While the continuously moving web is slowed to match the speed of the component parts, the parts are transferred to the web and the speed of the web is then accelerated to gather the festoons prior to the next cycle.
Another method is the so-called "slip gap" method in which the parts or components are cut from a web of material moving at a slower speed than the product web. As the component parts are cut from the first web of material, they are held to either the anvil roller or the cutter roller by means of vacuum. As the pieces pass tangentially to the continuously moving product web which is moving at a different speed, the parts or components slip temporarily until they are vacuum transferred to the continuously moving product web.
These known methods of transferring component parts, moving at one speed, to a continuously moving web moving at a different speed, do not address the problem of insuring careful registration of the deposited component parts on the continuously moving web. The problem is exacerbated when the need exists for depositing two or more components, one on top of the other on the continuously moving web while insuring careful registration of one component to the other, or to the moving web.
There remains a need for an efficient process for depositing workpiece components moving at different web speeds on a substrate web which process insures accurate registration of the parts with respect to one another.